Container-packed milk coffee beverage

ABSTRACT

Provision of a packaged milk coffee beverage having excellent hypertensive effects. A packaged milk coffee beverage satisfying the following conditions (A) to (C):
         (A) from 0.01 to 1 wt % of chlorogenic acids,   (B) less than 0.1 wt % of hydroxyhydroquinone based on a content of the chlorogenic acids, and   (C) a pH of from 5.0 to 6.4.

FIELD OF THE INVENTION

This invention relates to a packaged milk coffee beverage that is suppressing hydroxyhydroquinone after the treatment of heat sterilization and has hypotensive effects.

BACKGROUND OF THE INVENTION

Examples of existing therapeutic agents for hypertension include a variety of neuroleptics acting on the regulation system associated with neural factors, ACE inhibitors acting on the regulation system related to liquid factors, AT acceptor antagonists, Ca antagonists related to the regulation system associated with substances derived from the vascular endothelial, and antihypertensive diuretics related to the hemoral modulation system in the kidneys. These therapeutic agents are used primarily for treating serious hypertensive patients at medicinal institutions. Under present circumstances, however, such medicines for hypertension are forcing the patients to bear heavy burdens due to adverse side effects thereof, though their effectiveness is satisfactory.

Meanwhile, an alimentary therapy, an exercise therapy and general therapies for the improvements of lifestyle such as restrictions of drinking and smoking are widely employed for patients ranging from high normal blood-pressure patients, including mildly hypertensive patients, to severely hypertensive patients. As the importance of general therapies is increasingly acknowledged, the importance of improved dietary life continues to be talked about especially. There are a number of foods known as having hypotensive effects. Intensive searches for antihypertensive materials derived from food have conventionally conducted, and many effective ingredients have been isolated and identified so far.

Among them, chlorogenic acids, caffeic acids, ferulic acids, which are contained in foods such as coffee, have been reported to show excellent hypertensive effects (Patent Documents 1 to 3). However, coffee beverages containing chlorogenic acids in large quantity are also reported to have no plainly recognizable hypotensive effects and tend to increase the blood pressure to the contrary (Non-patent Document 1).

-   -   [Patent Document 1] JP-A-2002-363075     -   [Patent Document 2] JP-A-2002-22062     -   [Patent Document 3] JP-A-2002-053464     -   [Non-patent Document 1] Eur. J. Clin. Nutr., 53(11), 831 (1999).

DISCLOSURE OF THE INVENTION

The present invention provides a packaged milk coffee beverage satisfying the following conditions (A) to (C):

(A) from 0.01 to 1 wt % of chlorogenic acids,

(B) less than 0.1 wt % of hydroxyhydroquinone based on a content of the chlorogenic acids, and

(C) a pH of from 5.0 to 6.4.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a packaged milk coffee beverage, which has excellent hypertension-alleviating effects and can be ingested routinely.

The present inventors focused on the fact that coffee beverages do not show sufficient hypotensive effects despite their inclusion of chlorogenic acids, and thus conducted various investigations on possible correlations between hypotensive effects and coffee beverage ingredients. As a result, it has been found that hydroxyhydroquinone contained in coffee beverages inhibits the hypotensive effects of chlorogenic acids. It has also been found that a coffee composition having excellent hypotensive effects can be obtained when the content of hydroxyhydroquinone is reduced to a specific level lower than its general content while maintaining the content of chlorogenic acids within a predetermined range.

However, it has been found that, when the coffee composition is formulated into a packaged milk coffee beverage by adding a milk ingredient, hydroxyhydroquinone increases during a heat sterilization process, even if the content of hydroxyhydroquinone is reduced beforehand. As a result of a further investigation, it has been found that the increase of hydroxyhydroquinone by heat sterilization process was successfully inhibited by controlling the pH of the beverage to a predetermined range and a packaged milk coffee beverage of good flavor and taste can be obtained.

The packaged milk coffee beverage according to the present invention has excellent hypertension-alleviating effects, i.e., antihypertensive effects or blood-pressure-suppressing effects, and can be continuously ingested over a long term. The packaged milk coffee beverage according to the present invention is, therefore, useful as a medicine for the alleviation of hypertension or as a beverage labeled to the effect that it can be used for hypotension or for the suppression of an increase in blood pressure or labeled: “for those having higher blood pressure”.

From the standpoints of hypotensive effects, blood-pressure-suppressing effects and taste, the packaged milk coffee beverage according to the present invention contains from 0.01 to 1 wt %, preferably from 0.05 to 0.8 wt %, more preferably from 0.1 to 0.6 wt %, even more preferably from 0.13 to 0.5 wt %, even more preferably from 0.15 t 0.4 wt % of chlorogenic acids (A). As the chlorogenic acids (A), three chlorogenic acids, that is, (A¹) monocaffeoylquinic acid, (A²) feruloylquinic acid and (A³) dicaffeoylquinic acid are contained. As monocaffeoylquinic acid (A¹), one or more monocaffeoylquinic acids selected from 3-caffeoylquinic acid, 4-caffeoylquinic acid and 5-caffeoylquinic acid can be mentioned. As feruloylquinic acid (A²), one or more feruloylquinic acid selected from 3-feruloylquinic acid, 4-feruloylquinic acid and 5-feruloylquinic acid can be mentioned. As dicaffeoylquinic acid (A³), one or more dicaffeoylquinic acids selected from 3,4-dicaffeoylquinic acids, 3,5-dicaffeoylquinic acids and 4,5-dicaffeoylquinic acids can be mentioned. The content of such chlorogenic acids can be measured by high-performance liquid chromatography (HPLC). As a detection method in HPLC, UV detection is general, but detection at still higher sensitivity is also feasible by CL (chemical luminescence) detection, EC (electrochemical) detection, LC-Mass detection or the like.

The content of hydroxyhydroquinone (B) in the packaged milk coffee beverage according to the present invention is less than 0.1 wt % based on the content of the chlorogenic acids. When the content of hydroxyhydroquinone based on the content of chlorogenic acids is less than 0.1 wt %, the hypotensive effects of the chlorogenic acids can be fully exhibited. The content of hydroxyhydroquinone based on the content of chlorogenic acids maybe preferably from 0.001 to 0.08 wt %, more preferably from 0.002 to 0.05 wt %, even more preferably from 0.003 to 0.04 wt %, even more preferably from 0.004 to 0.03 wt %. Further, when the content of hydroxyhydroquinone is 0.05 wt % or less based on the content of chlorogenic acids, the hypotensive effects appear pronouncedly. It is to be noted that the content of hydroxyhydroquinone in the beverage according to the present invention may be 0.

The content of such hydroxyhydroquinone can be measured by high-performance liquid chromatography (HPLC). As a detection method in HPLC, UV detection is general, but detection at still higher sensitivity is also feasible by CL (chemical luminescence) detection, EC (electrochemical) detection, LC-Mass detection or the like. Among them, EC (electrochemical) detection is preferred in that it can measure even a very trace amount of hydroxyhydroquinone. It is to be noted that upon measurement of the content of hydroxyhydroquinone in a coffee beverage or the like by HPLC, the measurement maybe conducted after its concentration.

Although the content of hydroxyhydroquinone can be directly measured by HPLC, hydroxyhydroquinone can also be quantitated by concentrating it from a packaged milk coffee beverage or milk coffee composition in accordance with one of various chromatographic technologies and measuring the amount of the fraction of its concentrate.

It is to be noted that upon measurement of the content of chlorogenic acids, the measurement may preferably be conducted on a solution prepared by diluting the packaged milk coffee beverage tenfold, for example, with a 5% acetonitrile solution, which contains 50 mM acetic acid, 10 mM sodium acetate and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid, or in a 4 to 5 (V/V) % acetonitrile solution system, which contains 40 to 50 mM acetic acid, 9 to 10 mM sodium acetate and 0.09 to 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid, immediately after opening the packaged milk coffee beverage. It is also to be noted that upon measurement of hydroxyhydroquinone, the measurement may preferably be conducted on a solution prepared by diluting the packaged milk coffee beverage two fold with a 5 (V/V) % methanol solution, which contains 0.5 (W/V) % phosphoric acid and 0.5 mM 1-hydroxyethane-1,1-diphosphonic acid, or in a 2.5 to 5 (V/V) % methanol solution system, which contains 0.25 to 0.5 (W/V) % phosphoric acid and 0.25 to 0.5 mM 1-hydroxyethane-1,1-diphosphonic acid, immediately after opening the packaged milk coffee beverage.

The pH of the packaged milk coffee beverage according to the present invention after its heat sterilization treatment is from 5.0 to 6.4, preferably from 5.4 to 6.4, more preferably from 5.5 to 6.3. If the pH of the beverage is lower than 5.0, the flavor, taste and stability of the beverage deteriorate although the amount of hydroxyhydroquinone to be formed is reduced. If it exceeds pH 6.4, on the other hand, the amount of hydroxyhydroquinone to be formed increases. As a pH adjustment, it is preferred to test beforehand a change in pH by heat sterilization treatment and to adjust the pH before heat sterilization by predicting the pH after the heat sterilization treatment, because the pH changes through heat sterilization. The pH of the milk coffee composition before heat sterilization may be approximately from 5.2 to 6.7, preferably from 5.6 to 6.6, more preferably from 5.7 to 6.5. A pH adjustment can also be effected by such an operation as causing the pH to return to the above-described range under aseptic conditions after heat sterilization.

The packaged milk coffee beverage according to the present invention may preferably contain general coffee components as they are, except for the reduction of the content of hydroxyhydroquinone.

In the packaged milk coffee beverage according to the present invention, the content of H₂O₂ (hydrogen peroxide) may be preferably 1 ppm or lower, more preferably 0.1 ppm or lower, even more preferably 0.05 ppm or lower, even more preferably 0.01 ppm or lower from the standpoint of the inherent flavor and taste of coffee. The measurement of hydrogen peroxide can be conducted with any hydrogen peroxide meter employed in common. For example, “SUPER ORITECTOR MODEL 5” (high-sensitivity hydrogen peroxide meter manufactured by CENTRAL KAGAKU CORP.) or the like can be employed. H₂O₂ should be promptly analyzed immediately after opening the package in accordance with the measurement conditions described in U.S. Pat. Nos. 3,732,782 and 3,706,339, especially because H₂O₂ has been eliminated by sterilization processing before the opening of the package but, when exposed to air as a result of the opening of the package, H₂O₂ tends to gradually increase with time.

No particular limitation is imposed on the variety of coffee beans to be used for the packaged milk coffee beverage according to the present invention, and Brazil, Columbia, Tanzania, Moca and the like can be mentioned as examples. As species of coffee, there are Arabic species and Robusta species. Single variety of coffee beans can be used, or plural varieties of coffee beans can be blended and used. No particular limitation is imposed on the roasting method for roasted coffee beans, and no limitations are imposed either on the roasting temperature and roasting atmosphere. Accordingly, an ordinary roasting method can be adopted. Moreover, no limitation is imposed either on the method of extraction from the beans. There can be mentioned, for example, a method that extracts coffee from roasted coffee beans or a grounded product thereof with water to hot water (0 to 100° C.) for from 10 seconds to 30 minutes. Extraction methods can include the boiling process, the espresso process, the siphon process, the drip process (paper, flannel or the like).

As milk ingredients useful in the packaged milk coffee beverage according to the present invention, fresh milk, milk, whole milk powder, skimmed milk powder, fresh cream, concentrated milk, skimmed milk, partially-skimmed milk, condensed milk, vegetable milk, and the like. These milk ingredients may be contained preferably at from 0.1 to 10 wt %, more preferably at from 0.5 to 6 wt %, even more preferably at from 1 to 4 wt % in total in terms of milk solid in the packaged milk coffee beverage .

The packaged milk coffee beverage according to the present invention generally means one prepared by using coffee beans as much as 1 g or more, preferably 2.5 g or more, more preferably 5 g or more in terms of green beans per 100 g. Further, the packaged milk coffee beverage may preferably be “single-strength”. The term “single-strength” as used herein means a packaged milk coffee beverage which is ready for drinking, as it is, without needing dilution after being opened.

The milk coffee composition useful for the packaged milk coffee beverage according to the present invention can be obtained by treating an extract of roasted coffee beans with an adsorbent to lower the content of hydroxyhydroquinone and adjusting the pH to from 5.2 to 6.7. As the adsorbent, activated carbon, a reversed-phase chromatography medium or the like can be mentioned. More specifically, it can be only necessary to add an adsorbent to an extract of roasted coffee beans or an aqueous solution of a dry product of an extract of roasted coffee beans, to stir them at from 0 to 100° C. for from 10 minutes to 5 hours, and then to remove the adsorbed. The adsorbent may preferably used 0.02 to 1.0 times as much as the weight of roasted coffee beans in the case of activated carbon, or 2 to 100 times as much as the weight of roasted coffee beans in the case of a reversed-phase chromatography medium. For activated carbon, the average pore radius in the micropore range may be preferably 5 Angstroms (Å) or smaller, more preferably in a range of from 2 to 5 Angstroms, even more preferably in a range of from 3 to 5 Angstroms. The term “micropore range” as used herein means 10 Angstroms and smaller, and as the average pore radius, the value of a pore radius corresponding to the peak top of a pore size distribution curve obtained by conducting a measurement by the MP method was employed. The MP method is the pore size measurement method described in a technical paper (“Colloid and Interface Science”, 26, 46(1968)), and is the method adopted by Sumika Chemical Analysis Service, Ltd. and Toray Research Center, Inc.

As the kind of activated carbon, palm shell activated carbon is preferred, with steam-activated palm shell activated carbon being more preferred. As commercial products of activated carbon, “SHIRASAGI WH2C” (Japan EnviroChemicals, Ltd.), “TAIKO CW” (Futamura Chemical Industries Co., Ltd.), “KURARAY COAL GW” (Kuraray Chemical Co. , Ltd.) and the like can be used. As reversed-phase chromatography carriers, “YMS•ODS-A” (YMC Co., Ltd.) , “C18” (GL Science, Inc.) and the like can be mentioned.

Among these adsorbent treatment methods, an adsorbent treatment method making use of specific activated carbon is preferred because it is not only capable of selectively lowering the content of hydroxyhydroquinone without reducing the content of chlorogenic acids but also industrially advantageous and moreover, it does not lower the content of potassium (retains is at ⅕ or higher, preferably ½ or higher in weight ratio).

The packaged milk coffee beverage according to the present invention may preferably have no substantial peak in the time range of from 0.54 to 0.61 in terms of relative retention time to gallic acid when gallic acid is used as a standard substance in an analysis by HPLC. For the confirmation of the existence of no substantial peal in the time range, general HPLC can be used. For example, this confirmation can be effected by using as an eluent a gradient eluent of a 0.05 M solution of acetic acid in water and a 0.05 M solution of acetic acid in 100% acetonitrile as an eluent and an ODS column and performing detection with an ultraviolet absorptiometer or the like.

The possession of no substantial peak by the relative retention time to gallic acid in the time range of from 0.54 to 0.61 in the present invention means S2/S1<0.01, in which S1 represents an area value obtained upon analysis of a 1 ppm solution of gallic acid and S2 represents the sum of peak areas ascribable to components eluted in the above-described time range when the packaged milk coffee beverage is analyzed under the same conditions.

To the packaged milk coffee beverage according to the present invention, sugars such as sucrose, glucose, fructose, xylose, fructose-glucose solution and sugar alcohol, antioxidants, pH regulators, emulsifiers, flavors and the like can be added.

As the ratio of constituents in monocaffeoylquinic acid in the packaged milk coffee beverage, it is preferred the weight ratio of 4-caffeoylquinic acid/3-caffeoylquinic acid is from 0.6 to 1.2 and the weight ratio of 5-caffeoylquinic acid/3-caffeoylquinic acid is from 0.01 to 3.

As the package of the packaged milk coffee beverage according to the present invention, a container such as a PET bottle, a can (aluminum or steel), a paper pack, a retort pouch or a bottle (glass) can be used. In this case, a container of from 50 to 2, 500 mL can be used. From the viewpoint of preventing changes in the components of coffee, a container of low oxygen permeability is preferred as the container. For example, the use of an aluminum or steel can, a glass bottle or the like is preferred. In the case of cans and bottles, recappable and resealable ones are also included. The term “oxygen permeability” means an oxygen permeability (cc·mm/m²·day·atm) as measured under an environment of 20° C. and 50% relative humidity by an oxygen permeability meter for containers and films, and an oxygen permeability of 5 or lower can be preferred, with 3 or lower being more preferred, with 1 or lower being even more preferred.

Upon production of a packaged milk coffee beverage, sterilization processing is generally conducted. When heat sterilization is feasible, the sterilization processing is conducted under the sterilization conditions prescribed in the Food Sanitation Act after being filled in a container such as a metal can. For those which cannot be subjected to retort sterilization like PET bottles or paper packs, a process is adopted such that the coffee beverage is sterilized beforehand at a high temperature for a short time under similar sterilization conditions as the conditions prescribed in the Food Sanitation Act, for example, by a plate-type heat exchanger, is cooled to a particular temperature, and is then filled in a package.

The packaged milk coffee beverage according to the present invention contains an effective amount of chlorogenic acids having hypertension-alleviating effects and, even after heat sterilization processing, is lowered in the content of hydroxyhydroquinone which inhibits the hypertension-alleviating effects of hydroxyhydroquinone. It is, therefore, useful as a hypotensive or blood-pressure-suppressing medicinal composition, a hypotensive beverage or a blood-pressure-suppressing beverage.

Examples

Analytical methods of chlorogenic acids and hydroxyhydroquinone are as follows:

Analytical Method of Chlorogenic Acids

An analytical method of chlorogenic acids in a packaged milk coffee beverage or milk coffee composition is as will be described hereinafter. HPLC was used as an analyzer. The followings are the model numbers of component units in the analyzer. UV-VIS detector: “L-2420” (Hitachi High-Technologies Corporation), column oven: “L-2300” (Hitachi High-Technologies Corporation), pump: “L-2130” (Hitachi High-Technologies Corporation), autosampler: “L-2200” (Hitachi High-Technologies Corporation), column: “CADENZA CD-C18”, 4.6 mm inner diameter×150 mm length, particle size: 3 μm (Intact Corp.).

Analysis conditions are as follows. Sample injection volume: 10 μL, flow rate: 1.0 mL/min, wavelength preset for UV-VIS detector: 325 nm, preset column-oven temperature: 35° C., Eluent A: 5 (V/V) % acetonitrile solution containing 0.05 M of acetic acid, 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid and 10 mM sodium acetate, Eluent B: acetonitrile.

Concentration Gradient Conditions

Time Eluent A Eluent B  0.0 min 100% 0% 10.0 min 100% 0% 15.0 min 95% 5% 20.0 min 95% 5% 22.0 min 92% 8% 50.0 min 92% 8% 52.0 min 10% 90% 60.0 min 10% 90% 60.1 min 100% 0% 70.0 min 100% 0%

In HPLC, a sample (1 g) was accurately weighed, its total volume was increased to 10 mL with Eluent A, and subsequent to filtration through a membrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science, Inc.), the filtrate was provided for an analysis.

Retention Time of Chlorogenic Acids (Unit: min)

(A^(l)) Monocaffeoylquinic acid: 3 kinds at 5.3, 8.8 and 11.6 in total, (A²) feruloylquinic acid: 3 kinds at 13.0, 19.9 and 21.0 in total, and (A³) dicaffeoylquinic acid: 3 kinds at 36.6, 37.4 and 44.2 in total. From the area values of the 9 kinds of chlorogenic acids as determined above, 5-caffeoylquinic acid was chosen as a standard substance, and its wt % was determined.

Analytical Method of Hydroxyhydroquinone by HPLC-Electrochemical Detector

An analytical method of hydroxyhydroquinone in a packaged milk coffee beverage or milk coffee composition is as will be described hereinafter. As an analyzer, an HPLC-electrochemical detector (the coulometric type) “COULARRAY SYSTEM” (model: 5600 A, developed and manufactured by: ESA Analytical, Ltd., imported and sold by: MC MEDICAL, INC.), HPLC-electrochemical detector (the coulometric type), was used. The followings are the names and model numbers of component units in the analyzer.

Analytical cell: “MODEL 5010”, coularray organizer, coularray•electronics module software: “MODEL 5600A”, solvent feeder module: “MODEL 582”, gradient mixer, autosampler: “MODEL 542”, pulse damper, degasser: “DEGASYS ULTIMATE DU3003”, column oven “505” . Column: “CAPCELL PAK C18 AQ”, 4.6 mm inner diameter×250 mm length, particle size: 5 μm (Shiseido Co., Ltd.).

Analysis conditions are as follows.

Sample injection volume: 10 μL, flow rate: 1.0 mL/min, voltage applied to electrochemical detector: 0 mV, preset column-oven temperature: 40° C., Eluent A: 5 (V/V) % methanol solution containing 0.1 (W/V) % phosphoric acid, and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid, Eluent B: 50 (V/V) % methanol solution containing 0.1 (W/V) % phosphoric acid and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid.

For the preparation of Eluent A and Eluent B, distilled water for high-performance liquid chromatography (Kanto Chemical Co., Ltd.), methanol for high-performance liquid chromatography (Kanto Chemical Co., Ltd.), phosphoric acid (guaranteed reagent, Wako Pure Chemical Industries, Ltd.) and 1-hydroxyethane-1,1-diphosphonic acid (60% aqueous solution, Tokyo Kasei Kogyo Co., Ltd.) were used.

Concentration Gradient Conditions

Time Eluent A Eluent B  0.0 min 100% 0% 10.0 min 100% 0% 10.1 min 0% 100% 20.0 min 0% 100% 20.1 min 100% 0% 50.0 min 100% 0%

After a sample (5 g) was accurately weighed, its total volume was increased to 10 mL with a 5 (V/V) % methanol solution containing 0.5 (W/V) % phosphoric acid and 0.5 mM 1-hydroxyethane-1,1-diphosphonic acid. The solution was subjected to centrifugation to obtain an analysis sample of the supernatant. The supernatant was allowed to pass through “BOND ELUTE SCX” (packed weight of solid phase: 500 mg, reservoir capacity: 3 mL, GL Science, Inc.), and an initial volume (approx. 0.5 mL) of passed solution was diverted to obtain the passed solution. The passed solution was subjected to filtration through a membrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science, Inc.), and the filtrate was promptly provided for its analysis.

In an analysis by the HPLC-electrochemical detector under the above-described conditions, the retention time of hydroxyhydroquinone was 6.38 minutes. From the area values of peaks obtained, their weight percentages were determined by using hydroxyhydroquinone (Wako Pure Chemical Industries, Ltd.) was a standard substance.

Example 1

Medium roast coffee beans were extracted with 8 volumes of deionized water (95° C.) to obtain a coffee extract. The Brix degree of the coffee extract was next measured, and a column (inner diameter: 45 mm, length: 150 mm) packed with activated carbon (“SHIRASAGI WH2C”) in an amount as much as 50 wt % of the Brix degree was provided. Subsequently, the coffee extract was allowed to pass under the conditions of 25° C. and SV 8 [1/capacity [m³]/flow rate [m³/hr]] through the column packed with the activated carbon to subject the coffee extract to activated carbon treatment, and therefore, a coffee composition from which hydroxyhydroquinone had been removed was obtained.

The content of CGA in the coffee composition obtained with hydroxyhydroquinone removed therefrom as described above was measured. The coffee composition was diluted with deionized water, milk was added to amount to 11.5%, and its pH was adjusted with sodium bicarbonate such that its pH value after heat sterilization processing became equal to the corresponding value shown in Table 1. Hydroxyhydroquinone before the heat sterilization was lower than its detection limit (the analytical method of hydroxyhydroquinone by HPLC-electrochemical detector). The coffee composition obtained as described above was filled in a 190-g can, sealed, and subjected to retort sterilization processing under the sterilization conditions shown in Table 1 to obtain a packaged milk coffee beverage. For the hydroxyhydroquinone after the heat sterilization, the analytical method of hydroxyhydroquinone by HPLC-electrochemical detector was employed.

Examples 2-3 & Comparative Example 1

Packaged milk coffee beverages were produced in a similar manner as in Example 1 except that their pH values after heat sterilization processing became equal to the corresponding values shown in Table 1.

Example 4

Through a column (inner diameter: 45 mm, length: 150 mm) packed with activated carbon (“SHIRASAGI WH2C”) in an amount as much as 50 wt % of the Brix degree of a medium roast coffee extract, the coffee extract was allowed to pass under the conditions of 25° C. and SV 8 [1/capacity [m³]/flow rate [m³/hr]].

Into a solution with an emulsifier, casein Na and skimmed milk powder dissolved beforehand therein, milk, an aqueous sugar solution and the above-described coffee extract treated with the activated carbon were mixed. The mixture was subjected to a pH adjustment with an aqueous solution containing sodium bicarbonate dissolved therein, and was then diluted with deionized water such that the content of CGA was lowered to 170 mg/100 g.

The thus-obtained coffee composition was filled in a 190-g can, sealed, and subjected to retort sterilization processing at 135° C. for 100 seconds to produce a packaged milk coffee beverage.

Comparative Example 2

Through a column (inner diameter: 45 mm, length: 150 mm) packed with activated carbon (“SHIRASAGI WH2C”) in an amount as much as 50 wt % of the Brix degree of a medium roast and light roast, mixed coffee extract, the mixed coffee extract was allowed to pass under the conditions of 25° C. and SV 8 [1/capacity [m³]/flow rate [m³/hr]].

Into a solution with an emulsifier, casein Na and skimmed milk powder dissolved beforehand therein, milk, an aqueous sugar solution and the above-described coffee extract treated with the activated carbon were mixed. The mixture was subjected to a pH adjustment with an aqueous solution containing sodium bicarbonate dissolved therein, and was then diluted with deionized water such that the content of CGA was lowered to 350 mg/100 g.

The thus-obtained coffee composition was filled in a 190-g can, sealed, and subjected to retort sterilization processing at 135° C. for 100 seconds to produce a packaged milk coffee beverage.

Comparative Example 3

Through a column (inner diameter: 45 mm, length: 150 mm) packed with activated carbon (“MOLSIEVON X2M”) in an amount as much as 50 wt % of the Brix degree of a dark roast coffee extract, the coffee extract was allowed to pass under the conditions of 25° C. and SV 8 [1/capacity [m³]/flow rate [m³/hr]].

Into a solution with an emulsifier, casein Na and skimmed milk powder dissolved beforehand therein, milk, an aqueous sugar solution and the above-described coffee extract treated with the activated carbon were mixed. The mixture was subjected to a pH adjustment with an aqueous solution containing sodium bicarbonate dissolved therein, and was then diluted with deionized water such that the content of CGA was lowered to 170 mg/100 g.

The thus-obtained coffee composition was filled in a 190-g can, sealed, and subjected to retort sterilization processing at 127° C. for 11 minutes to produce a packaged milk coffee beverage.

Results

As shown in Table 1 and Table 2, it has been found that the increase of hydroxyhydroquinone after heat sterilization can be inhibited by controlling the pH after heat sterilization processing to from 5.0 to 6.4.

<Specific Example of Processing before the Measurement of Chlorogenic Acids>

Immediately after a packaged milk coffee was opened, a portion (1 g) was accurately weighed. Its total volume was then increased to 10 mL with Eluent A (5 (V/V) % solution of acetonitrile containing 50 mM acetic acid, 10 mM sodium acetate and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid). Subsequent to filtration through a membrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science, Inc.), the filtrate was provided for its analysis.

<Specific Example of Processing before the Measurement of Hydroxyhydroquinone>

Immediately after a packaged milk coffee was opened, a portion (5 g) was accurately weighed. Its total volume was increased to 10 mL with a 5 (V/V) % methanol solution containing 0.5 (W/V) % phosphoric acid and 0.5 mM 1-hydroxyethane-1,1-diphosphonic acid. The solution was subjected to centrifugation to obtain a supernatant. The supernatant was allowed to pass through “BOND ELUTE JR SCX” (packed weight of solid phase: 500 mg, GL Science, Inc.), and an initial volume (approx. 1.0 mL) of passed solution was diverted to obtain the passed solution. The passed solution was subjected to filtration through a membrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science, Inc.), and the filtrate was promptly provided for its analysis.

<Specific Example of a Measurement of Hydrogen Peroxide>

“SUPER ORITECTOR MODEL 5” (CENTRAL KAGAKU CORP.), a hydrogen oxide analyzer, was used. After it was calibrated with a standard calibration solution (hydrogen peroxide: 1 ppm), aliquots (1 mL) of 0.2 M phosphate buffer (pH 7.0) with 0.5% potassium bromate added therein were placed in measurement cells of the analyzer, respectively. At the time point that dissolved oxygen in the cell had been reduced to zero as a result of feeding of nitrogen, a commercial canned coffee and a test sample both of which had been allowed to stand in a 30° C. constant-temperature chamber were opened, and aliquots (1 mL) were promptly sampled and placed in the measurement cells, respectively. The measurement procedure of the analyzer was then followed to read the concentrations of produced oxygen from its printer. If extrapolation is needed, the oxygen concentrations are measured at every 15^(th) minute, the data up to 1 hour later are used to draw a straight line by the method of least squares, and then, the content of hydrogen peroxide is determined. The detection limit of “MODEL 5” was 0.1 mg/kg.

<Evaluation of Flavor and Taste>

Three expert panelists drank and evaluated each beverage at 25° C. shortly after its opening.

TABLE 1 Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 <Sterilization conditions> Sterilization temperature ° C. 123.5 123.5 123.5 123.5 Sterilization time min 25 25 25 25 F0 value 43.4 43.4 43.4 43.4 <pH before sterilization processing> 5.5 5.8 6.5 5.0 Hydroxyhydroquinone before sterilization processing (analyzed wt % 0 0 0 0 by HPLC-electrochemical detector) <Analysis data after sterilization processing> Chlorogenic acids (CGA) wt % 0.177 0.177 0.171 0.174 Hydroxyhydroquinone (analyzed by HPLC-electrochemical detector) wt % 0.000037 0.000046 0.000072 0.000033 Hydroxyhydroquinone/chlorogenic acids × 100 wt % 0.021 0.026 0.042 0.018 pH 5.3 5.6 6.3 4.8 4-Caffeoylquinic acid/3-caffeoylquinic acid wt. ratio 0.953 0.940 0.922 0.974 5-Caffeoylquinic acid/3-caffeoylquinic acid wt. ratio 1.199 1.094 1.04 1.449 H₂O₂ content mg/kg <DL* <DL* <DL* <DL* Flavor and taste Good Good Good Sour taste & flavor & flavor & flavor & unpleasant taste taste taste taste DL: detection limit

TABLE 2 Comp. Comp. Ex. 4 Ex. 2 Ex. 3 <Sterilization conditions> Sterilization temperature ° C. 135 135 127 Sterilization time min 1.67 1.67 11 F0 value 40.9 40.9 42.8 <pH before sterilization processing> 6.6 6.6 6.7 Hydroxyhydroquinone before sterilization processing wt % 0 0 0.00134 (analyzed by HPLC-electrochemical detector) <Analysis data after sterilization processing> Chlorogenic acids (CGA) wt % 0.167 0.325 0.16 Hydroxyhydroquinone (analyzed by HPLC- wt % 0.000041 0.000083 0.0018 electrochemical detector) Hydroxyhydroquinone/chlorogenic acids × 100 wt % 0.024 0.025 1.122 pH 6.3 6.5 6.6 4-Caffeoylquinic acid/3-caffeoylquinic acid wt. ratio 0.75 0.73 0.81 5-Caffeoylquinic acid/3-caffeoylquinic acid wt. ratio 0.9 0.81 1.03 H₂O₂ content mg/kg <DL* <DL* <DL* Flavor and taste Good flavor Unpleasant Unpleasant & taste taste taste DL: detection limit

Referential Example 1

A coffee beverage Q was produced by the following procedure.

Production of Coffee Treated with Activated Carbon

After a commercial instant coffee (“NESCAFE®, Gold Blend Red Label”) (20 g) was dissolved in distilled water (1,400 mL) (the thus-prepared coffee will be called “a coffee composition P”), activated carbon “SHIRASAGI WH2C 28/42” (Japan EnviroChemicals, Ltd.) (30 g) was added. Subsequent to stirring for 1 hour, the mixture was filtered through a membrane filter (0.45 μm) to obtain a filtrate (this coffee will be called “a coffee composition Q”). The thus-obtained filtrate was lyophilized to afford a brown powder (15.8 g). That brown powder was dissolved in distilled water, and chlorogenic acids and hydroxyhydroquinone were quantitated by HPLC analysis. Chlorogenic acids and hydroxyhydroquinone were found to be contained at 4.12 wt % and lower than detection limit, respectively. Further, the content of potassium was also measured by ICP emission spectroscopy. The potassium content was found to be approx. 4.2 wt % in both the instant coffee as the raw material and the coffee treated with the activated carbon.

Referential Example 2

Evaluation of the hypotensive effects of the coffee composition Q prepared in Referential Example 1.

Experimental Materials and Procedure

-   (a) After 13 to 14 weeks old, male spontaneously hypertensive rats     (SHR) had been fully acclimatized to a blood pressure measurement     procedure by provisionally measuring their blood pressures for 5     straight days with a commercial indirect blood-pressure meter for     rats (manufactured by Softron Co., Ltd.), an evaluation test was     performed. The rats were all reared under the conditions of 25±1°     C., 55±10% R. H. and 12 hr lighting time (7:00 a.m. to 7:00 p.m.)     (in rat-zone rearing rooms). -   (b) Administration method and given dose: In the test group, the     coffee composition Q (coffee treated with activated carbon) prepared     in Referential Example 1 was used. In the control group, the     commercial instant coffee was used. The coffee treated with the     activated carbon and the instant coffee were separately dissolved in     aliquots of physiological saline to prepare coffee beverages such     that they would each give a dose of 200 mg/kg in terms of total     chlorogenic acid dose. As their administration method, they were     orally administered with feeding needles. The given dose was set at     5 mL/kg. -   (c) Testing method: Four to six SHRs were used per group. The     systolic blood pressure in the caudal vein was measured before the     oral administration and also 12 hours after that, and the percentage     blood pressure change after 12 hours was calculated from the blood     pressure before the administration. -   (d) Statistical processing method: From the measurement results so     obtained, the means and standard deviations were calculated and a     Student's t-tests was conducted. The significance level was set at     5%.

Results: As evident from Table 3, a pronounced hypotension was recognized from the ingestion of the coffee composition Q compared with the ingestion of the general instant coffee.

TABLE 3 Control group Test group Administered coffee Instant coffee Coffee composition Q # of cases 4 6 Percentage blood −5.1 −10.0* pressure change (%) (12 hours after administration) Standard deviation 1.0 0.6 *Had a significant difference from the control group at a percentage of risk not greater than 5%. 

1. A packaged milk coffee beverage satisfying the following conditions (A) to (C): (A) from 0.01 to 1 wt % of chlorogenic acids, (B) less than 0.1 wt % of hydroxyhydroquinone based on a content of said chlorogenic acids, and (C) a pH of from 5.0 to 6.4.
 2. The packaged milk coffee beverage according to claim 1, wherein a weight ratio of 4-caffeoylquinic acid to 3-caffeoylquinic acid is from 0.6 to 1.2, and a weight ratio of 5-caffeoylquinic acid to 3-caffeoylquinic acid is from 0.01 to
 3. 3. The packaged milk coffee beverage according to claim 1 or 2, wherein an oxygen permeability of a package is not higher than 5 [cc·mm/m²·da·atm]. 